wich filters are better?

[sharky]

hi guys!

wich filters are better for 3d projection? linear or circular ones?

bye

sharky

[Likay]

I can say that the ordinary linear polarized filters are both cheaper and works just as well as the more expensier circular polarizers regarding 3d projection. I've tried both of them (Using camerapolarizers) but not noticing any remarkable difference.

[DDuckMan]

I can say that the ordinary linear polarized filters are both cheaper and works just as well as the more expensier circular polarizers regarding 3d projection. I've tried both of them (Using camerapolarizers) but not noticing any remarkable difference.

I thought linear polarizers were sensative to head movement (tilt)?

[sharky]

that is exactly what i thought too....

[Likay]

Yes, they are. But that goes for the circular too. I've also heard that circular is better if tilting your head but it's of no difference.

[Jahun]

Likay, how are your filters now?


I played quite a bit on my cheapos and they still work perfectly, I don't see burn in yet. However... yours give 2x more light, I might want to go that direction in the near future too.. You do have normal linear ones too right? Is it an obvious jump in brightness?

Ow and btw, I don't have much problems with head tilting... the ghosting becomes obvious only in really awkward gaming positions

[Likay]

In the waiting for the new SPAR-filter i used one of my camera filters for about 30 hours of gameplay. This time i mounted them about 7-8 cm's from the beamerlens. This time nothing happened. The filters seems to be very temperature sensitive though since i never had a temp over 50?C.
Should be good news for you Jahun.

My SPAR-filters works perfectly and i'm a very happy passive projectionrig owner. It was quite a hazzle getting the filters since they only had a left eye filter to send. But now everything's all right and they even sent me 10 extra glasses!

I tried to assemble retarders and a linear polarization foil to establish the same (or close to) effect as with the SPARS... Had absolutely no luck... lol
I guess SF engineers know exactly what they're doing. I managed to get good results with one color, but the overall performance went to h-l....

I give a rapidshare link here to the pics. I have one projector going in these pics on low radiation (2000 A-lumen). The lamp in the ceeling contains a 40W bulb (just for reference). The camera lightsensitivity and focus is locked to give best comparison. At least it give some kind of hint though. Also added one pic of my temporary projector holder!

http://rapidshare.com/files/49256117/Fi ... s.rar.html

cheers

[Jahun]

Thanks for all that info Likay!

My filters now have also 25 to 50 hours of gameplay on them and so far I can't notice anything. I hope they'll keep this up.. worst case I make new ones (plenty material left) and put a small fan on them or place them further.

Great pair of photos and I dig your projectormounting! Never seen that approach before Who cares anyway, if it works

I can really see the difference in those images, and I can use those SPAR's. My projectors are just 1000 lumen, which I want for movies in my perfectly dark room. But with 3D that becomes more like 330 lumen which is a bit low. Those SPAR's would imprve that, but for now I'll be just fine. 330 is very doable if you can elimate all light.

A 40W bulb like you is impossible though.. but you have SPAR's and 2000 lumens, that;s cheating!

Thanks again.. those pictures help estimating what it will look like..


I am not amazed it didn't work for you to make them yourself. I am working on a physics Phd and don't understand all that is needed too. Yitzhak told me once he used 15 layers to get his SPAR's. And I guess those 15 are thickness tailored too.

(wave plates work depending on thickness, a single one you can rotate to increase effective thickness, but they work differently for any wavelength so you will need many of them to compensate and rotate all colors correctly I think)

[Likay]

Well, this projectorrig is temporary (has been quite some time now) but i'm planning for a decent projectorstand. lol. That picture was sent only to cheer someone up. hehe

If only the colors from the beamers were alingned the same way, a simple QW-retarderfoil between the beamer and the polarizationfilter would have been enough. But now that's not the fact... At least i gave it a shot though. I like to make experiments.

ps: Your 2 cents here and there makes a fortune in the end.

cheers

[Tril]

I bought linear filters from polarization.com and from American Polarizers.

The polarization.com filters
I got a big sheet. There is enough material to make about 8 filters.
It is made of plastic and is thick enough to give it some rigidity and it's slightly flexible.
It's polarized along the length of the sheet.
Cheap.

The American Polarizers filters
I got two squares of 4 inch by 4 inch. I think that they can make them in any size you request.
They have an anti-reflective coating on both sides.
It's polarized at 45 degres.
It's about 4 times more costly than the polarization.com sheet.

I made a very quick comparison test. The test showed no major difference of how good they polarize light.

Theorically, the American Polarizers filters should give a better picture because they are made out of glass, they are perfectly flat and they have an anti-reflection coating. I need to make two sturdy holders to test them more properly.

[Jahun]

Great, though I wonder if you will see a difference... Personally I doubt it.
Perhaps in a perfect test image, but not in a gaming environment.

Likay, I looked into that too. A bit much also.. even asked a optics friend of mine..

A Quarter Wave retarder plate would give you circular polarised light.. that works (though glasses more expensive etc). You could also use a half wave plate to rotate the linear polarised light to another degree (45/-45).

But as you said, LCD's have their polarisations of the colors not in the same plane. On top of that, its polarisation is quite crappy. On my projectors blue and red are quite good, but green is really badly polarised. That prohibits me from trying StereoBright method which would give even more light output than the SPAR's.

I tried to ask around, if it is possible to tingle with the projectors and open them up and mess with the polarisations before all the colors are recombined in the x-prism. Haven't had responses yet though. (I guess that means it won't work, that or they are making/patenting it as we speak)

Ow and btw.. I think Barco uses a technique like the SPAR's on their high output 3D projectors ($$$$$$$$$$)..

[Likay]

It seems like passive projection is a growing interest here. In that case the prices of stereopol-(SP) technique will probably drop quite an amount and quite quickly too!. No matter what: When using dlp and polarized technique you're only able to use maximum 45% of the light output. With LCD's and stereopol-technique you can get up to 75% output. That made my decision... Had to save money for quite some time more though... lol
One backside with lcd's is that they cannot be completely "blacked out". Dlp's are much better in that. But this might be a advantage when used in polarized rigs to help drown the ghosting (just a theory) and resulting in very low experienced ghosting.

cheers

[Jahun]

Yep I'm quite convinced about LCD technology and passive too